In recent years, the need for mobile electronic devices such as mobile phones and notebook computers has been increased. For such electronic devices, development of thin mobile terminals having audio functions as commodity values such as television phones, video playing, and hands-free phones is underway. Within such development, there is an increasing demand for high sound quality and a decrease in the size and thickness of an electroacoustic transducer (a speaker device) which is an acoustic component.
Currently, in electronic devices such as mobile phones, an electrodynamic electroacoustic transducer is used as the electroacoustic transducer. The electrodynamic electroacoustic transducer is configured by permanent magnets, voice coils, and vibrating diaphragm.
However, the electrodynamic electroacoustic transducer has a limitation on reduction of thickness due to its operating principle and structure. Meanwhile, Patent Documents 1 and 2 describe use of a piezoelectric vibrator as the electroacoustic transducer.
In addition, as additional examples of an oscillator using a piezoelectric vibrator, apart from a speaker device, a variety of electronic devices such as a sound wave sensor that detects the distance and the like to a subject using sound waves emitted from a piezoelectric vibrator (refer to Patent Document 3), are also known.